Chemistry Reference
In-Depth Information
PARAFFIN NAMES
1
2
3
4
5
6
CH
3
CH
CH
2
CH
CH
2
CH
3
CH
3
CH
CH
3
CH
3
2-methyl-4-isopropyl hexane
Name base: longest straight chain of carbon atoms
Numbered to give the lowest sum
The alkyl groups attached to the carbon base are methyl and isopropyl
More complicated paraffinic hydrocarbons take their names from the longest
chain of carbon atoms. In the name the atoms are numbered so that the sum
of the atoms bearing substituent groups (side chains) is the lowest. The side
chains (alkyl groups) are described as being attached to a numbered carbon
atom. In the above example, the longest straight chain is six carbons, so the
compound is a hexane with the isopropyl group attached to carbon atom 4 and
the methyl group to carbon atom 2. Had the hexane chain been numbered in
reverse, the compound would be 3-isopropyl-5-methyl hexane. However,
because the sum of 2
+
4 is less than 3
+
5, the correct name is 2-methyl-4-
isopropyl hexane.
